A place to stay near Boulogne-Billancourt University Hospital while Florence receives treatment

My wife Florence has been accepted for treatment at Boulogne-Billancourt University Hospital in Boulogne-Billancourt, starting on Saturday in June. We live 522 km away in a town in the north, and hotel costs would use up what we have set aside for the treatment itself. We're looking for a room, granny flat or short-term rental within about 30 minutes of the hospital, for 3 weeks. Two of us would stay: Florence and me. We can contribute $100 a week and cook for the household if you'd like. Florence will have some immune precautions, so a clean, smoke-free place would be ideal. A kitchen is a bonus. Thank you. Please ask me anything in the questions section. I'll answer honestly and quickly.